Re: LNT, regs and lives

["Otto G. Raabe" <ograabe@ucdavis.edu>]

September 7, 1999
Davis, CA

[REPEATED WITH MORE INFORMATION]

The supporters of the LNT hypothesis for radiation carcinogenesis are
sustained primarily by the reports from RERF in which linear models are
used to evaluate the atomic bomb survivor data. The three points that seem
to be consistently raised are these:

(1) In studies of the atomic bomb survivors reported by the Radiation
Effects Research Foundation, Pierce et al. (Rad. Research 146:1-27, 1996)
showed a statistically significant increase in solid tumor incidence at
0.05 Sv compared to smaller doses and supralinearity (bigger slope) at low
doses (higher than linear risk). This is the most recent major RERF report
on radiation carcinogenesis in atomic bomb survivors.

(2) Doll and Wakeford (Br. J. Radiol. 70: 130-139, 1997) analyzed the Alice
Stewart et al. studies of childhood cancer in children whose mothers had
been X-rayed during pregnancy and showed a statistically significant
increase in cancer for doses about or lower than 10 mGy (0.01 Sv) and a
risk slope of 6% per Sv, which agrees with the linear model predictions.
These are extensive studies over many years initiated by Dr. Alice Stewart
(now 91 years of age) which are called the Oxford Survey of Childhood
Cancer (OCSS).

(3) Dan Benison says everyone agrees that the risk is linear above 0.2 Sv
and since we all receive this much exposure during a normal lifetime from
normal background radiation, we are all up the linear curve. So, the shape
of the dose-response curve at lower doses is unimportant. Dan Benison is
the former ICRP member who developed the theoretical arguments for use of
the LNT to estimate cancer risk.

If you want to talk LNT with its proponents, you need to address these
points. I every recent meeting that I have attended where LNT was
discussed, these were their key arguments.

Otto 
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